4.PRESENT PERFECT

A.WHEN TO USE:                       
there are basically three uses for the present perfect tense: 
1.experience
2.change
3.continuing situation 

1.present perfect tense for experience 

we often use the present tense to talk about experience. from the past. we are not interested in when you did something. we only want to know if you did it.

i have seen et.
he has lived in bangkok.
have you been there?
we have never eaten caviar.

PAST                           PRESENT                    FUTURE
the action or                  in my head                  
state was in                   i have a                                
the past                        memory now        

connection with past: the event was in the past         
connection with present: i know something aboul the event; i have experience of it.

2.present perfect tense for change
we also use the present perfect tense to talk about change or new information

I HAVE BOUGHT A CAR

                           PAST                                 PRESENT  +                               FUTURE

           last week i didn't have a car               now, i have a car                   

JHON HAS BROKEN HIS LEG

                          PAST +                                   PRESENT  -                            FUTURE  

          yesterday john had a good leg           now he has abad leg     

HAS THE PRICE GONE UP?

                          PAST +                                   PRESENT -                             FUTURE

        was the prince $1.50 yesterday?      is the prince $1.70 today        

connetion with past: the past is the epposite of the present.

   

connection with present: the present is the opposite of the past

3.PRESENT PERFECT TENSE FOR CONTINUING SITUATION

we often use the present perfect tense to talk about a continuing situation. this is a state that started in the past and continues in the present. (and will probably continue into the future). this is a state (not an action). we usually use for or since with this structure.

i have worked here since june he has beenill for 2 days how long have you known tara?

          

                                    past                               present                             future

                   the situation starte in the past   it continues up to now     (it will probably continue into the future)

connection with past: the situation starte in the past

connection with present: the situation continues in the present   

STRUCTURE
POSITIVE FORM

SUBJECT + (HAVE/HAS + PAST PARTICIPLE) + COMPLEMENT
.I/we/you/they have been to brasil
.he/she/it has eaten sushi

NEGATIVE FORM
SUBJECT + (HAVEN'T/HASN'T + PAST PARTICIPLE + COMPLEMENT

I/we/you/they haven't  been to brasil
he/she/it hasn't eaten sushi

question form 
(have/has + subject + past participle + complement 

      question word     auxiliary     subject        past participle  complement
      what countries       have     i/we/you they         been               to?
                                    has        he/she/it              eaten             sushi?